With 13K+ battles under your belt, I can only suppose you already tried the game settings, but it never hurts to try them again. I used to fly with both radars on (radar and barometric). I don't know if the GPWS system is tied to the radar altimeter being on. Have you tried it?

I do. It spewed out warnings like "Excessive diving!" when you were in a dive and close to the ground. But I usually paid more attention to the radar alt, mainly in maps like the new National Park and Fjords.